age =12
if age<10:
    print("小孩")
elif age>=10 and age<20:
    print("小朋友")
elif age>=20 and age<30:
    print("年轻人")
elif age>=30 and age<50:
    print("中年人")
elif age>50:
    print("老年人")
else:
    print("输入有误")